1. Field of the Invention
The present invention relates generally to a vibration insulator of the fluid filled type which includes a main working chamber and a plurality of auxiliary chambers and associated orifice passages, and more specifically to such a type of insulator which features a partition construction which is used to define the auxiliary chambers and which increases the sealing therebetween.
2. Description of the Prior Art
FIG. 11 shows an vibration insulator of the nature disclosed in JP-A-2-42227, which finds particular application in suspension arrangements which are used to support an internal combustion engine on an automotive chassis.
As shown, this type of insulator 100 comprises inner and outer tubular members 102, 104 and an elastomeric body 106 which is disposed therebetween. The elastomeric body 106 is apertured in a manner which defines a main working chamber 108, the volume of which varies with the vibration induced relative displacement between the inner and outer members 102, 104.
The construction further includes: first and second orifice or control passages 110, 114 which extend about the inner periphery of the outer member 104 and which respectively establish fluid communication between the main working chamber 108 and first and second auxiliary or expansion chambers 112, 116. The first orifice or control passage 110 is dimensioned to produce a fluid flow resistance which enables the slug of working fluid contained therein, to resonate in response to a relatively low frequency high amplitude type vibration (e.g. frequ=10 Hz, amp .+-.1 mm) and thus enable engine shake type vibration to be damped effectively.
On the other hand, the second orifice passage is dimensioned so that the slug of working fluid therein resonates in response to the application of a vibration having a frequency of 20-30 Hz and an amplitude of approximately .+-.0.3 mm. Viz., a vibration of the nature produced when an internal engine is idling.
This construction enables two different types of engine vibration to be effectively attenuated.
With this type of vibration insulator, the first and second auxiliary chambers can be defined by a partitioning assembly of the nature generally denoted by the numeral 126 and which, as shown in FIG. 12, is comprised of first and second elements 120 and 122 formed by press working sheet metal, and which are arranged to be fitted one on the other.
However, with the above type of partition assembly construction, in the event that the two members 120, 122 are not fitted together in exactly the correct manner and the device is assembled with the deviation uncorrected, the slight misalignment therebetween can lead to the formation of small gaps and leakage which results in a loss of vibration damping efficiency.